Production and characterisation of a SARSCoV-2 S-protein RBD homodimer with increased avidity for specific antibodies.

Monitoring of the proportion of immune individuals and the effectiveness of vaccination in a population involves evaluation of several important parameters, including the level of virus-neutralising antibodies. In order to combat the COVID-19 pandemic, it is essential to develop approaches to detecting SARS-CoV-2 neutralising antibodies by safe, simple and rapid methods that do not require live viruses. To develop a test system for enzyme-linked immunosorbent assay (ELISA) that detects potential neutralising antibodies, it is necessary to obtain a highly purified recombinant receptor-binding domain (RBD) of the spike (S) protein with high avidity for specific antibodies. The aim of the study was to obtain and characterise a SARSCoV-2 S-protein RBD homodimer and a recombinant RBD-expressing cell line, as well as to create an ELISA system for detecting potential neutralising antibodies. Material(s) and Method(s): the genetic construct was designed in silico. To generate a stable producer cell line, the authors transfected CHO-S cells, subjected them to antibiotic pressure, and selected the optimal clone. To isolate monomeric and homodimeric RBD forms, the authors purified the recombinant RBD by chromatographic methods. Further, they analysed the activity of the RBD forms by Western blotting, bio-layer interferometry, and indirect ELISA. The analysis involved monoclonal antibodies GamXRH19, GamP2C5, and h6g3, as well as serum samples from volunteers vaccinated with Gam-COVID-Vac (Sputnik V) and unvaccinated ones. Result(s): the authors produced the CHO-S cell line for stable expression of the recombinant SARS-CoV-2 S-protein RBD. The study demonstrated the recombinant RBD's ability to homodimerise after fed-batch cultivation of the cell line for more than 7 days due to the presence of unpaired cysteines. The purified recombinant RBD yield from culture broth was 30-50 mg/L. Monomeric and homodimeric RBD forms were separated using gel-filtration chromatography and characterised by their ability to interact with specific monoclonal antibodies, as well as with serum samples from vaccinated volunteers. The homodimeric recombinant RBD showed increased avidity for both monoclonal and immune sera antibodies. Conclusion(s): the homodimeric recombinant RBD may be more preferable for the analysis of levels of antibodies to the receptor-binding domain of the SARS-CoV-2 S protein.Copyright © 2023 Authors. All rights reserved.

A Customized Novel Blocking ELISA for Detection of Bat-Origin Swine Acute Diarrhea Syndrome Coronavirus Infection.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a newly discovered emerging alphacoronavirus. SADS-CoV shares over 90% genome sequence identity with bat alphacoronavirus HKU2. SADS-CoV was associated with severe diarrhea and high mortality rates in piglets. Accurate serological diagnosis of SADS-CoV infection is key in managing the emerging SADS-CoV. However, thus far there have been no effective antibody-based diagnostic tests for diagnose of SADS-CoV exposure. Here, monoclonal antibody (MAb) 6E8 against SADS-CoV N protein accurately recognized SADS-CoV infection. Then, MAb 6E8 was utilized as a blocking antibody to develop blocking ELISA (bELISA). We customized the rN coating antigen with concentration 0.25 µg/mL. According to receiver operator characteristic curve analysis, the cutoff value of the bELISA was determined as 38.19% when the max Youden index was 0.955, and specificity was 100%, and sensitivity was 95.5%. Specificity testing showed that there was no cross-reactivity with other serum positive swine enteric coronaviruses, such as porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), porcine rotavirus (PoRV), and porcine sapelovirus (PSV). In conclusion, we customized a novel and high-quality blocking ELISA for detection of SADS-CoV infection, and the current bELISA will be linked to a clinical and epidemiological assessment of SADS-CoV infection. IMPORTANCE SADS-CoV was reported to be of high potential for dissemination among various of host species. Accurate serological diagnosis of SADS-CoV infection is key in managing the emerging SADS-CoV. However, thus far there have been no effective antibody-based diagnostic tests for diagnose of SADS-CoV exposure. We customed a novel and high-quality bELISA assay for detection of SADS-CoV N protein antibodies, and the current bELISA will be linked to a clinical and epidemiological assessment of SADS-CoV infection.

Prevention of COVID-19 coronavirus infection with aminodihydrophthalazinedione sodium (Galavit) in medical staff of the "red zone": results of the multicenter observational study

COVID-hospital healthcare workers belong to a high-risk SARS-CoV-2 infection. The aminodihydrophthalazinedione sodium (Galavit) belongs to the group of immunomodulatory and anti-inflammatory drugs. It has been shown that aminodihydrophthalazinedione sodium is effective in the prevention of acute respiratory infections, respiratory tract diseases and ENT-organs of bacterial and viral etiology. The purpose of the study. To evaluate the effectiveness and safety of immunoprophylaxis of new coronavirus infection (COVID-19) with aminodihydrophthalazinedione sodium in healthcare workers providing medical care in the "red zone". Material and methods. A multicenter prospective-retrospective observational comparative non-randomized study in healthcare workers providing medical care in the "red zone" was conducted. 428 participants were included in the study: the observation group - healthcare workers who administered aminodihydrophthalazinedione sodium (Galavit) for prophylactic purposes (n=214), and control group (n=214). The observation period of the participants or the period of collecting retrospective data in the study was 30 days. The results of PCR tests and tests for antibodies to the SARS-CoV-2 were analyzed, clinical status (COVID-19 in any form) was assessed. Descriptive statistic methods and Pearson chi2 test were used. The risk ratios, odds ratios and 95% confidence intervals were calculated with them. The influence of potential confounding factors (age, gender, work place in clinical site, the presence or absence of concomitant disease) on the clinical status were analyzed using logistic regression. The analysis of propensity score matching was carried out. The Stata/IC 14.2 for Windows software used for statistical analysis. Results and discussion. Observational study results describe the risk ratios and odds ratios of infection with a new coronavirus (COVID-19) in healthcare workers providing medical care in the "red zone" considering prophylactic administration of aminodihydrophthalazinedione sodium (Galavit). 205 (95.8%) participants in the group of healthcare workers who took aminodihydrophthalazinedione sodium (Galavit) for prophylactic purposes and 194 (90.7%) participants in control group had a negative PCR test during the observation period, chi2=4.48, p=0.034. The risk of a positive status according to the PCR test for 30 days in the preventive group was 0,04, and in the control group 0.09. The risk difference was -0.05 [95% confidence interval (CI) -0.099;-0.004]. The adjusted odds ratio using multiple logistic regression was - 0.41 (95% CI 0.18-0.93). No adverse events were observed during the prophylactic administration of aminodihydrophthalazinedione sodium over 30 days. Conclusion. Galavit preventive administration in a tablet form at a dose of 50-100 mg per day by employees of medical institutions providing medical care to patients with CIVID-19 significantly reduces the risk of SARS-CoV-2 infection and more than 2 times increases the chances not ill of new coronavirus infection. Galavit administration up to 30 days at a dose of 50-100 mg was well tolerated, no adverse events were registered.Copyright © 2022 by the authors.

Determination of antibodies to SARS-CoV-2 in patients with coronavirus infection

COVID-19, caused by the novel SARS-CoV-2 virus, poses major challenges for global public health. The detection of antibodies in blood serum is one of the important methods for diagnostics of COVID-19 patients. The main aim was to study the dynamics of the appearance of neutralizing antibodies and antibodies to the SARS-CoV-2 proteins in COVID-19 patients sera. Material and methods. The blood sera of four groups of people were studied: "intact" donors (blood sera were collected in 2016-2019);patients with a laboratory-confirmed diagnosis of acute respiratory viral infection;patients with influenza (antibodies to the influenza virus have been identified) and patients with a PCR confirmed diagnosis of COVID-19. Blood sera were analyzed in ELISA with commercial kits for detection of IgG to SARS-CoV-2 (N, S) proteins and total antibodies to RBD of protein S and in neutralization test (NT). Results and discussion. Antibodies to SARS-CoV-2 were not detected in paired blood sera of people from groups 1-3 by ELISA and NT. At the time of hospitalization of patients with COVID-19 in the sera of 12 (19%) patients antibodies to SARS-CoV-2 were absent when they were determined by NT and ELISA. In blood sera taken 4-9 days after hospitalization, neutralizing antibodies and antibodies to at least one viral protein were detected in ELISA. Conclusion. At the time of hospitalization, the overwhelming majority of patients had a humoral immune response to the SARS-CoV-2. In the dynamics of observation, the levels of antibodies to SARS-CoV-2 proteins increased, to a greater extent to RBD.Copyright © 2022 Geotar Media Publishing Group

Frequency of SARS-CoV-2 infection in hemodialysis patients

Patients with end-stage chronic kidney disease treated with hemodialysis are at risk of infection and severe course of the new coronavirus infection. This opinion was based on the data obtained as a result of PCR testing during the active phase of the disease with detailed clinical symptoms. However, this diagnostic method does not allow one to fully assess the prevalence of infection in the population. The aim - studying of the frequency of SARS-CoV-2 infection in patients receiving hemodialysis treatment and the spectrum of antiviral antibodies, depending on the nature of the course of COVID-19. Material and methods. 100 patients with chronic kidney disease (stage 5D) treated at the outpatient Dialysis Center (MCVTP) were included in the study by a simple random sample. The assessment of SARS-CoV-2 infection was carried out by analyzing the material of smears obtained from the naso-oropharynx by PCR and blood serum samples by ELISA. The study excluded 14 patients with dubious results for the determination of serological markers SARS-CoV-2 and 1 patient with active infection, who was isolated from the RNA of the virus. Results. IgM and IgG antibodies were detected in 49 (57.6%) of the 85 examined patients. 24 of them (group 1) were diagnosed with COVID-19 infection with typical clinical symptoms 3-9 months ago, and 25 (group 2) had no clinical manifestations of the acute respiratory infection at the appropriate time suggesting an asymptomatic course of the disease. IgM class antibodies were detected with equal frequency in group 1 and in group 2 (33.3 vs 24.0%, respectively, p<0.6). IgG antibodies exclusively to the nucleocapsid N-protein (IgGn) were detected only in the latent form of the disease (32%), while antibodies against the S-protein (spike protein) of the virus (IgGs and IgGn+s) were detected more often in the manifest form compared to the asymptomatic one (100 vs 60%, respectively, p<0.05). Conclusion. In a random cohort of patient receiving hemodialysis treatment, more than half were asymptomatic.Despite a wide range of prevention measures, SARS-CoV-2 infection among patients treated with hemodialysis is more than 2 times higher than in the general population.Copyright © 2021 Geotar Media Publishing Group. All rights reserved.

Incidence and sero-surveillance of feline viruses in Korean cats residing in Gyeonggi-do

Incidences of major feline viral diseases provide basic information for preventing viral disease in cats. Despite the growing interest in feline viral diseases, sero-surveillances have been lacking. In this study, we analyzed the diagnoses of feline viral diseases and conducted a sero surveillance of feline panleukopenia virus (FPV), feline calicivirus (FCV), feline herpesvirus-1 (FHV-1), and feline infectious peritonitis virus (FIPV) in Korean cats. Of the 204 confirmed cases since 2015, the numbers of diagnoses for FPV, FIPV, FCV, feline influenza virus, and FHV-1 were 156, 32, 12, 3, and 1 case, respectively. In total, 200 sera, collected between 2019 and 2021, were screened for the presence of antibodies against FPV, 2 FCVs, FHV-1, and FIPV using a hemagglutination inhibition test and a virus-neutralizing assay (VNA). The overall seropositive rates in cats tested for FPV, the 2 FCVs, FHV-1, and FIPV were 92.5%. 42.0%, 37.0%, 52.0%, and 14.0%, respectively. A low correlation (r = 0.466) was detected between the VNA titers of 2 FCV strains. The highest incidence and seropositive rate of FPV reveal that FPV is circulating in Korean cats. The low r-value between 2 FCVs suggests that a new feline vaccine containing the 2 kinds of FCVs is required.

Clinical validation of novel dried blood spot based collecting device using serum separation for measuring SARS-CoV-2 antibodies.

Accurate surveillance of coronavirus disease 2019 (COVID-19) incidence includes large-scale antibody testing of the population. Current testing methods require collection of venous blood samples by a healthcare worker, or dried blood spot (DBS) collection using finger prick, however this might have some logistic and processing limitations. We investigated the performance of the Ser-Col device for detecting severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies using a finger prick: DBS-like collection system that includes a lateral flow paper for serum separation and allows for automated large scale analysis. For this prospective study, adult patients with moderate to severe COVID-19 were included 6 weeks post-symptom onset. Healthy, adult volunteers were included as a negative control group. Venous blood and capillary blood using the Ser-Col device were collected and the Wantai SARS-CoV-2 total antibody ELISA was performed on all samples. We included 50 subjects in the study population and 49 in the control group. Results obtained with venous blood versus Ser-Col capillary blood showed 100% sensitivity (95% CI: 0.93-1.00) and 100% specificity (95% CI: 0.93-1.00). Our study shows the feasibility of SARS-CoV-2 total antibody screening using a standardized DBS technique with semiautomated processing for large scale analysis.

Engineering highly efficient NIR-II FRET platform for Background-Free homogeneous detection of SARS-CoV-2 neutralizing antibodies in whole blood.

Förster or fluorescence resonance energy transfer (FRET) enables to probe biomolecular interactions, thus playing a vital role in bioassays. However, conventional FRET platforms suffer from limited sensitivity due to the low FRET efficiency and poor anti-interference of existing FRET pairs. Here we report a NIR-II (1000-1700 nm) FRET platform with extremely high FRET efficiency and exceptional anti-interference capability. This NIR-II FRET platform is established based on a pair of lanthanides downshifting nanoparticles (DSNPs) by employing Nd3+ doped DSNPs as an energy donor and Yb3+ doped DSNPs as an energy acceptor. The maximum FRET efficiency of this well-engineered NIR-II FRET platform reaches up to 92.2%, which is much higher than most commonly used ones. Owing to the all-NIR advantage (λex = 808 nm, λem = 1064 nm), this highly efficient NIR-II FRET platform exhibits extraordinary anti-interference in whole blood, and thus enabling background-free homogeneous detection of SARS-CoV-2 neutralizing antibodies in clinical whole blood sample with high sensitivity (limit of detection = 0.5 µg/mL) and specificity. This work opens up new opportunities for realizing highly sensitive detection of various biomarkers in biological samples with severe background interference.

Room-temperature-storable chemiluminescence freeze-drying mixes for detection of SARS-CoV-2 neutralizing antibody

As the vaccine was successfully developed, the spread of the epidemic (COVID-19) was effectively controlled. But there are still thousands of people affected COVID-19 after being vaccinated. Neutralizing activity has become a critical method for quantifying neutralizing antibody against SARS-CoV-2. However, limited to the strict conditions of cold chain transportation, the neutralizing activity test has not been widely promoted. In this study, a room-temperature-storable chemiluminescence freeze-drying mixes for SARS-CoV-2 neutralizing antibody detection was developed to decrease the cost of lyophilization step for promoting its application in third world countries. Several freeze concentrated solutions were used to protect the antigen bioactivity. The mixes can be stored at room temperature over 12 months and still exhibited great accuracy and precision. Thus, the proposed room-temperature-storable chemiluminescence freeze-drying mixes offers a cheap and stable storage method for SARS-CoV-2 neutralizing antibody detection and shows a great potential for promoting the neutralizing activity test.

Preparation and identification of broad-spectrum monoclonal antibodies against N protein of avian infectious bronchitis virus

[Objective] To prepare broad-spectrum monoclonal antibody against N protein of avian infectious bronchitis virus (IBV), so as to lay a foundation for identifying conservative domain epitope of N protein and establish a universal IBV detection method. [Method] N protein of GX-YL5, a representative strain of IBV dominant serotype in Guangxi, was expressed in prokaryote. BALB/c mice were immunized with the purified protein. After the serum titer of the immunized mice reached 104 or more, the splenocytes were fused with SP2/0 myeloma cells. After screening by indirect ELISA, monoclonal antibody was prepared by ascites-induced method. Western blotting, IFA and indirect ELISA were used to identify the titer, subtype, reaction specificity and cross-reaction spectrum. And the prepared monoclonal antibody was used for immunohistochemical detection. And the prepared monoclonal antibody was used to detect the IBV in the trachea and kidney tissues of SPF chickens artificially infected with 4 representative IBV variants (GX-N130048, GX-N160421, GX-QZ171023 and GX-QZ170728). [Result] The prepared monoclonal antibody N2D5 had a titer greater than 217 and its subtype was IgG2b. The Western blotting and IFA results showed that the monoclonal antibody N2D5 only reacted with IBV, and were negative with Newcastle disease virus (NDV), infectious laryngotracheitis virus (ILTV), avian metapneumovirus (aMPV), infectious bursal disease virus (IBDV), avian leukosis virus (ALV) and Marek's disease virus (MDV). Monoclonal antibody N2D5 reacted with many genotypes in China and all 7 serotypes of IBV currently prevalent in Guangxi, including commonly used standard strains, vaccine strains and field strains. Immunohistochemistry showed that the virus signals could be detected in the trachea and kidney tissues of SPF chickens at different time after artificial infection of 3 representative IBV strains from chicken and 1 isolated strain from duck, which further proved its broad spectrum. [Conclusion] The monoclonal antibody N2D5 of IBV prepared based on hybridoma technology belongs to the IgG2b subtype. It has the characteristics of high specificity, wide response spectrum and strong binding ability with IBV. It can be used as a specific diagnostic antibody for clinical diagnosis of IBV and the study of virus distribution.

Rapid cassette test results in anti-SARS-CoV-2 antibody screening verification by electrochemiluminescence immunoassay method

Objective: Since the resumption of face-to-face education in October 2020, which was suspended due to the COVID-19 pandemic, coincides with the period when SARS-CoV-2 infection rates in young adults are on the rise. This study focuses on the 2019 corona virus outbreak in young adults, the largest link in the chain of transmission, which can be defined as silent contagious agents. It is aimed to provide epidemiological data by detecting virus disease (COVID-19) seropositivity with two different serological methods, and to evaluate the symptom-test performance relationship of asymptomatic/mild symptom/symptomatic cases. Methods: A cross-sectional study was conducted with students studying at Cappadocia University health programs between December 2020 and February 2021 and who will attend practice courses face-to-face. Participants were surveyed about their COVID-19 symptoms and disease histories based on SARS-CoV-2 exposure. For SARS-CoV-2 antibody detection, blood samples were taken from the participants and investigated with a single lateral flow immunoAssay (LFIA, Novatech, Turkey) cassette test. The samples with positive test result were then SARS-CoV-2 Anti-N IgM+IgG;SARS-CoV-2 Anti-S IgM+IgG;SARS-CoV-2 Anti-RBD IgG;It was re-evaluated using the electrochemiluminescence immunoassay (ECLIA) method with the anti-SARS-CoV-2 kit (Roche, Germany). Results: Of the 239 samples participating in the study, 50 (20.9%) samples that were positive for SARS-CoV2 IgM/ IgG according to the LFIA method were then studied again with the ECLIA method. According to the ECLIA result, 72% (36/50) of individuals against both nucleocapsid (N) and spike (S) antigens, and 70% (35) against RBD antigen were seropositive. Based on the ECLIA test results, 239 samples were studied and 50 samples were found to be IgM/IgG positive, with a sensitivity of 64% and a specificity of 93%. Contingence history was reported in 46% (n=23) of patients who were seropositive by both methods, while 30% (n=15) showed a COVID-19 clinic. Fifty four percent (n=27) of the participants reported that they did not have a PCR (polymerase chain reaction) test, but antibody response was observed in all of them. Only 28% (n=14) of seropositive patients reported positive PCR results, and 4% of them stated that they had a chronic disease. It will be important to continue to observe the serological status of young people, particularly in the context of new COVID-19 variants and in the low interest in mass vaccination campaigns targeting young people. Conclusion: It is thought that the performance of ECLIA with rapid casette test does not have a good degree of agreement and confirmation with different immunoassay tests would be more useful for epidemiological surveillance. Especially the new COVID-19 in the context of the variants and targeting youth due to the lack of interest in vaccination champaigns continue to monitor the serological status of young people it will be important.

Partial recovery of SARS-CoV-2 immunity after booster vaccination in renal transplant recipients

The pandemic caused by the SARS-CoV-2 coronavirus has been especially detrimental to patients with end-stage renal disease. History with other vaccines suggests that patients with renal disease may not respond adequately to the SARS-CoV-2 vaccine. The aim of this study is to evaluate the immunity to SARS-CoV-2 mRNA vaccines in renal patients. Post SARS-CoV-2 vaccination first, and after the booster dose, antibodies and cellular immunity were studied in patients on hemodialysis (N = 20), peritoneal dialysis (N = 10) and renal transplantation (N = 10). After the two doses of vaccine, there was an effective immunity in dialysis patients, with 100% seroconversion and 87% detection of cellular immunity (85% in hemodialysis and 90% in peritoneal dialysis). In contrast, in renal transplant recipients there was only 50% seroconversion and cellular immunity was detected in 30% of patients. After the booster dose, all dialysis patients achieved a cellular and antibody immunity, whereas in transplant patients, despite improvement, 20% did not produce antibodies and in 37.5% cellular immunity could not be detected. The mRNA vaccine plus booster performs excellently in dialysis patients, whereas in kidney transplant recipients, despite the booster, complete immunization is not achieved.Copyright © 2022

RBD-Modified Polyaniline-Based Label-Free Immunosensor for Sensitive Impedimetric Detection of Anti-SARS-CoV-2 Antibodies

The emergence of the SARS-CoV-2 virus and the associated pandemic has affected the entire human population. Human susceptibility to the virus has highlighted a tremendous need for affordable diagnostic systems to manage the pandemic and monitor the effectiveness of vaccination. We have developed a simple and label-free electrochemical immunosensor for the detection of human anti-SARS-CoV-2 IgG antibodies, which consists of a supporting screen-printed carbon electrode (SPCE) modified with an electrodeposited polyaniline film and glutaraldehyde, allowing effective immobilization of the SARS-CoV-2 spike glycoprotein receptor-binding domain (RBD) as a biorecognition element. The impedimetric immunosensor showed a linear response over a wide concentration range of 0.01–10 μg mL−1, that is, 67 pM–6.7 nM, with a low detection limit of 25.9 pM. A dual working electrode configuration with a built-in negative control unit was demonstrated for practical field applications. The immunosensor was successfully used in a real serum sample from an infected patient and showed good reproducibility and fair agreement with ELISA. An optional amplification step with secondary goat anti-human IgG antibodies was demonstrated, resulting in an extended linear range and a detection limit as low as 0.93 pM.

Evaluation of the risks associated with the transmission of SARS-CoV-2 during a professional football club's training in Brazil

COVID-19 is an infectious disease with respiratory transmission caused by the new coronavirus. Due to the high viral transmissibility, sports activities were severely impacted all over the world and in Brazil football was paralyzed for about four months. The objective of this study was to identify the activities with the highest risk of Covid-19 transmission in a professional soccer club in Rio de Janeiro based on a cross-sectional study with a semi-quantitative emphasis. The results showed that physical training showed a greater number of touches (105) with a high prevalence of hand on the ball (94%). The antibody search found that 24,2% tested positive for IgG during the study. During the training phase, no cases of SARS-CoV-2 transmission between players and staff were identified. It is believed that biosafety measures and the individual and collective commitment of everyone to social isolation and hygiene measures are an important strategy for the viability of sports activities.

Influenza A and influenza B antibody determination in an Austrian cohort

Influenza is an infectious respiratory disease caused by influenza A and B, which is a virus characterized by a high mutation rate with new strains appearing regularly, making regular booster vaccinations necessary. In this study, we evaluated the immune status of Influenza A and B by using ELISA. A questionnaire was utilized to appraise the immunization anamnesis and the stance on vaccination. In total, 202 probands participated in this study. 35.6% of the probands were vaccinated, 10.9% indicated a confirmed influenza infection. 88.1% had a positive influenza A titer, whereas a positive influenza B titer was determined in only 38.6%. Additionally, a correlation between vaccination and titer could be observed. In this study, we were able to show a higher vaccination rate in our cohort than the Austrian average. Additionally, a higher percentage showed a positive influenza A titer compared to influenza B titer.Copyright © 2022

ANTI-SARS-CoV-2 SPIKE RECEPTOR BINDING DOMAIN (S-RBD) IgG ANTIBODIES FOLLOWING CoronaVac ADMINISTRATION: A LONGITUDINAL STUDY. ANTI-SARS-CoV-2 S-RBD IgG ANTIBODIES

Reports on antibody titers following CoronaVac administration are still scarce, particularly when it comes to the post-vaccination effectiveness of CoronaVac in the Indonesian population. The purpose of this study is to determine the efficacy of COVID-19 vaccination by comparing the IgG levels against the S1 subunit of SARS-CoV-2 RBD after the first and second vaccinations. The researchers collected venous blood samples from participants after they received the CoronaVac 600 SU/0.5 mL vaccine at two different intervals (14 days and 28 days). Blood was drawn twice (after the first and second vaccinations) and tested for antibodies (positive antibody detection value of 50 AU/mL). Paired data were analyzed by using either the Wilcoxon test (numerical) or the McNemar test (categorical). The median IgG1 levels in the 14-day interval between vaccine doses were 64.40 AU/mL and IgG2 levels were 886.10 AU/mL. Meanwhile, the median IgG1 level was 146.10, and IgG2 level was 688.00.AU/mL in the group with a 28-day interval between vaccine doses. After the first vaccination, 60.00 % of study subjects had positive IgG levels, which increased to 98.57% after the second vaccination. Following the full-dose vaccination, all participants had higher antibody levels, and considered significant. The effect was stronger in the group that received the vaccine at 14-day intervals. CoronaVac has also been shown to increase the prevalence of detectable antibody positivity in study participants.Copyright © 2023 Russian Association of Allergologists and Clinical Immunologists, St. Petersburg Regional Branch (SPb RAACI). All rights reserved.

Immunogenetics and SARS-CoV-2 infection

Since the beginning of the SARS-Cov-2 pandemic, in 2020, numerous data with respect to the influence of immunogenetics to the predisposition and infection severity have been reported worldwide. It is well accepted that immunogenetics plays a pivotal role in infection and vaccination, as well as vaccination failures and/or breakthrough. Factors of the major histocompatibility complex and the common ABO blood group system have been so far discussed. Here, we describe the association of HLA-A, -B, -C, -DRB1, -DRB345, -DQA1, -DQB1, -DPA1, -DPB1, and HLA-E, -F, -G, -H on the results of molecular detection of COVID-19 or in some cases on antibody detection upon first testing. Furthermore, we defined molecularly 22 blood group systems comprising 26 genes and 5 platelet antigen genes. We observed 37% COVID-19 PCR negative individuals and 63% positive. Within the negative subjects HLA-B*57:01, HLA-B*55:01, DRB1*13:01, DRB1*01:01, were enriched, and in the positive group homozygosity for DQA1/DQB1, DRB1*09:01 and DRB1*15:01. For HLA-DQA1 we observe an enrichment for DQA1*01:01, DQA1*02:01 and DQA1*01:03. For HLADQB1 we found HLA-DQB1*06:02 was enriched in the positive group while HLA-DQB1*05:01 and HLA-DQB1*06:03 in the negative group. We observed a significant enrichment of homozygosity for DQA1/DQB1 in the positive group. The homozygous platelet antigen HPA-1a was significantly enriched in the negative group, contrasting the result of HPA-1ab that was enriched in the COVID-19 infected group. Despite limitations of our study, the data presented here show clearly that COVID-19 infection and all the consequences of that are multifactorial and multigenetic. The virus is in a continuous mutation/selection process leading to escape possibilities. Therefore, associations are a momentum in science.

Detection of viral antibodies in camel sera using magnetic particle spectroscopy.

Pandemics like SARS-Cov-2 very frequently have their origin in different animals and in particular herds of camels could be a source of zoonotic diseases. This study took advantage on a highly sensitive and adaptable method for the fast and reliable detection of viral antibodies in camels using low-cost equipment. Magnetic nanoparticles (MNP) have high variability in their functionalization with different peptides and proteins. We confirm that 3-aminopropyl triethoxysilane (APTES)-coated MNP could be functionalized with viral proteins. The protein loading could be confirmed by simple loading controls using FACS-analysis (p < 0.05). Complementary combination of antigen and antibody yields in a significant signal increase could be proven by both FACS and COMPASS. However, COMPASS needs only a few seconds for the measurement. In COMPASS, the phase φn on selected critical point of the fifth higher harmonic (n = 5th). Here, positive sera display highly significant signal increase over the control or negative sera. Furthermore, a clear distinction could be made in antibody detection as an immune response to closely related viruses (SARS-CoV2 and MERS). Using modified MNPs along with COMPASS offers a fast and reliable method that is less cost intensive than current technologies and offers the possibility to be quickly adapted in case of new occurring viral infections. KEY POINTS: • COMPASS (critical offset magnetic particle spectroscopy) allows the fast detection of antibodies. • Magnetic nanoparticles can be adapted by exchange of the linked bait molecule. • Antibodies could be detected in camel sera without washing steps within seconds.

Specific antibodies of 95 health care workers vaccinated with inactivated 2019-nCoV vaccines

OBJECTIVE: To investigate the immune antibodies in blood specimens of 95 health care workers vaccinated with inactivated 2019-nCoV vaccines and explore the rules and characteristics of production of antibodies after vaccination. METHODS: From Oct 2020 to Jul 2021, the venous blood specimens were collected from 95 health care workers of the 305 Hospital of PLA after the injection of 2 doses of 2019-nCoV vaccines fo30 days, 65 days, 91 days, 6 months and 9 months. SARS-CoV-2 immunoglobin(Ig) M, IgG and titers of neutralizing antibodies and total antibodies were detected by chemiluminescence immunoassay, the results of antibody tests were dynamically analyzed, the immune durability of the antibody, influencing factors and correlation were determined. RESULTS: Almost all of the subjects produced IgG, neutralizing antibody and total antibody, some subjects retained high level of IgM titer. Smoking could affect the production of total antibody. The subjects of the low body weight group produced higher level of IgG, and there was no significant difference when the weight was over 60 kg. The titers of the four types of antibodies decreased significantly at the following time points, and the positive rates of all the antibodies were less than 50% except for IgG after the vaccination for 9 months. CONCLUSION: Specific IgM and IgG, neutralizing antibody and total antibody can be produced after the 2-doses vaccination of inactivated 2019-nCoV vaccines. But the titers and positive rates of the antibodies decrease with time, which means the protective effects on the body decrease. Therefore, in order to improve the autoimmunity against novel coronavirus, one booster vaccination of an inactivated 2019-nCoV vaccine will be necessary after the 2 doses of vaccination for 6 months.

Antibodies to the receptor-binding domain of the SARS-Cov-2 spike protein: association with age, pneumonia, duration of the period after COVID-19.

Despite the rapid accumulation of facts about the humoral immune response in COVID-19, there are still no evidence-based answers to questions about the factors influencing the level and duration of the detection period of antibodies to SARS-CoV-2 in the blood. Objective(s): To assess the prevalence, clinical and demographic associations of IgG antibodies to RBD of the SARSCoV-2 spike protein at different times after COVID-19. Materials and methods. Residents of the Altai region of Russia, Caucasians aged 20-93 years, who had COVID-19 from May 2020 to February 2021 (n = 314), took part in a onetime observational study. The level of antibodies in the blood was measured by enzyme-linked immunosorbent assay 1-14 months after the onset of the clinical manifestation of CO-VID-19. Results. Anti-RBD IgG antibodies of the SARS-CoV-2 spike protein were detected in 86.9% of the study participants. The dependence of the antibody titer on the duration of the period after COVID-19 was not revealed. The antibody titer was positively correlated with the complication of CO-VID-19 pneumonia and the volume of lung tissue lesions. The presence of pneumonia COVID-19 and the volume of lung tissue lesions are positively associated with age. Age positively correlated with antibody titer regardless of the pneumonia COVID-19 in the anamnesis. Conclusion. IgG antibodies to RBD of the SARS-CoV-2 spike protein are present in most of the COVID-19 patients. The titer of these antibodies in adults depends on age, complications of pneumonia COVID-19, and probably persists up to 14 months after the first symptoms of infection appear.Copyright © 2022 Interregional public organization Association of infectious disease specialists of Saint-Petersburg and Leningrad region (IPO AIDSSPbR). All rights reserved.